1. Field of the Invention
The present invention relates to a magnetic tape system and a tape drive for data recording, and particularly, to a magnetic tape system and a tape drive that enable high density recording and reproducing of data highly densely recorded.
2. Description of the Related Art
These years, in a magnetic tape high density recording progresses, and there is one that has a data capacity of around 200 GB for a backup of a computer. Therefore, on the magnetic tape several hundreds of data tracks are formed in lateral directions thereof. Accordingly, a width of the data tracks is designed to be very narrow, and a distance of neighboring data tracks is also very narrow. Consequently, in order to make write/read elements of a magnetic head trace the data tracks, in such a magnetic tape drive a servo signal is written in the magnetic tape in advance, and servo-controls a position of the magnetic head (position in lateral directions of the magnetic tape) while reading the servo signal with the magnetic head (JP 08-30942A (U.S. Pat. No. 5,689,384)).
Whereas, the width of the data tracks of the magnetic tape is designed to be extremely narrow such as several μm to several tens μm and is hereafter also foreseen to become narrower. Under such the condition, it is concerned that a deformation of the magnetic tape itself changes a pitch and positional relationship of the data tracks and influences on right and wrong of a tracking.
For example, because a magnetic tape is generally composed of a magnetic layer's being coated on a resin film, there occurs a change in a width of the magnetic tape by the resin film's swelling/drying or expanding/contracting. When such the change occurs after data recording on the magnetic tape, the pitch and positional relationship of data tracks on the magnetic tape do not match those of data read elements on a magnetic head, it cannot be avoided that part of the data tracks becomes off track by only tracking-control through the servo signal.
Not limited to the magnetic tape, such a problem similarly occurs in an optical tape for recording data by light.
Consequently, it is strongly requested a tape drive for data recording adequate for high density recording.